Lotus Elan

Which electronic ignition to choose ?

PostPost by: StoatWithToast » Mon Aug 01, 2011 2:25 pm

The 43D is just the later version of the 23D that was supplied as new from Lotus. There are some slight differences in look and function from the 23D, but as it is hidden away I don't worry (altough I'm still on the 23D)

The Aldon pre-fitted to my Sprint had an amazingly high level of scatter for a unit only ~3,000 miles old - to the point it was impossible to set the timing up on the car. I've heard other people say the same thing. I had purchased an Aldon unit to fit, as I thought I had broken points/condensor until I got into the thing and checked. I put a lot of the talk on here about bouncing rev counters after fitting these units being down to the rev counter trying to keep up with the random spark timing produced.
Now it has a Luminition optical unit fitted (as in the previously linked thread) - still waiting to put the engine back into the car, but on the bench it had almost no scatter and ran really well (bang on the money for a Big Valve twink). Also have a Luminition coil.
The install looks pretty nice and the only addition is the better connector to the coil and the metal control box in the engine bay - Luminition do a coil bracket to hold and help shield it to keep things neat.

I looked into the 123 system (have one on the XI - same running gear as a Sprite), but getting one modified to fit the jack gear and one that matched the advance curve turned into an expensive exercise (very expensive). They now do a fully programmable unit that you can plug into a PC, but that would still need to be modified to fit the engine drive.
'06 Elise SportsRacer 111R
'72 Sprint FHC (and staying that way) - 0479
'65 XI Replica
[And a Subaru, but I don't think that counts ;)]
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PostPost by: nebogipfel » Mon Aug 01, 2011 8:01 pm


Not sure what you mean by scatter? I've seen "tracking" within the distributer cap causing fluctuating timing.

Is this what you are referring to?

I've always assumed the Aldon and similar units are just on/off switches triggered by a magnetic field although my knowledge of such things is not good :oops:

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PostPost by: bob_rich » Mon Aug 01, 2011 8:02 pm

Hi Frank an others who may be interested.

For longer than I would wish to remember and since high voltage transistors became readily available I have built up transistor assisted points for all my cars I have ever owned. (Modern cars of course with ECU and FI dont need this). Generally with this circuit the points and there setting would last over 50,000 miles because they only interrupt a small cleaning current. Recently I further developed the circuit for a friend who had a GMC military truck of 1940's vintage with a 6 cylinder engine. It had a 6V +ve earth system and used to eat points. I developed my circuit into a better and tidier format on a PCB and put it in a diecast box. I ran one for around 1 year on my +2 B4 I stripped its down for its major rebuild, now on going. The design I now have can be built up 4 6V or 12V +ve or -ve earth. It fits into existing wiring and includes an LED for static timing. the big advantage over the modern point less systems is that it is very simple to return to original wiring by leaving everything as was.

If anyone is interested PM me 4 further info


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PostPost by: spridget » Thu Aug 04, 2011 1:20 pm

Hi all

Dave, on the Sprite I still have a classic point and condenser distributor.
It?s a small engine and the distributor is easy to work on.
Friends of mine use 123 ignition, expensive but as you mentioned it can be connected on a PC?. I?m working for a software company, I don?t want computer on my classic cars :mrgreen: !
Bob, thanks for your proposal, I understand the transistor to have a low current on the points. Here in France, we use to collect it from Renault Super 5 or Express, it is built by a make called ?Cartier?, so there are a few jokes about offering a jewel to our classics :D

To be honest, I think I was already convinced to by a new distributor from TTR, but it?s really helpful to have your opinion. I have ordered the kit and I hope to be able to reply in the next few weeks to tell you how it is on the +2

50/0302 +2, Frogeye
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PostPost by: jono » Wed Aug 10, 2011 10:12 am

.....the distributorless ignition system is not that complicated really.

Pics of my test rig - all works a treat :)

TW.JPG and
MJ.JPG and
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